x86/platform/UV: Prep for UV4 MMR updates

x86/platform/UV: Prep for UV4 MMR updates

Cleanup patch to rearrange code and modify some defines so the next
patch, the new UV4 MMR definitions can be merged cleanly.

* Clean up the M/N related address constants (M is # of address bits per
  blade, N is the # of blade selection bits per SSI/partition).

* Fix the lookup of the alias overlay addresses and NMI definitions to
  allow for flexibility in newer UV architecture types.

Tested-by: John Estabrook <estabrook@sgi.com>
Tested-by: Gary Kroening <gfk@sgi.com>
Tested-by: Nathan Zimmer <nzimmer@sgi.com>
Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Dimitri Sivanich <sivanich@sgi.com>
Cc: Andrew Banman <abanman@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <rja@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160429215403.401604203@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>